Cylinder plug for gas-operated guns with grenade launchers



Nov. 16, 1948.

C. H. COATES CYLINDER PLUG FOR GAS OPERATED GUNS WITH GRENADE LAUNCHERS Flled Jan 51, 1945 JIVUQ/MOD [3111114815 H. [Junie-.5

Patented Nov. 16, 1948 CYLINDER PLUG FORv GAS-OPERATED GUN S WITH GRENADE LAUNCHERS Charles H. Coates, Baton Rouge, La.

7 Application January 31, 1945, Serial No. 575,530

Claims. (ci ia-1i (Granted under the act of March 3, 1883, as-

The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment to me of any royalty thereon.

This invention relates to an improved gas cylinder plug for gas operated semi-automatic type rifles and it is especially designed for adapting such rifles to use with grenade launchers.

When rifles of the above described type are used in conjunction with grenade launchers for launching rifle or hand grenades, some means must be provided to reduce or eliminate the gas pressure which is produced in the gas cylinder of the piece, incident to the firing of the same, for the reason that the failure to do so will result in the piston rod in the cylinder being driven back with sufficient force to damage the working parts of the weapon.

As a result, a special grenade launcher and a special gas cylinder plug, to be used in conjuncamended April 30, 1928; 370 O. G. 757) ventional model M? rifle grenade launcher and tion therewith, has been developed for the rifle.

This plug is equipped with a valve which is held in an open position by a part of the grenade launcher, when the latter is applied to the rifle, to permit a portion of the gases, entering the gas cylinder, to escape therefrom through the gas cylinder plug, to thereby substantially reduce the pressure in the gas cylinder when ordinary ammunition is fired and thereby prevent the actuation'of the piston rod.

However, it is an object of this invention to provide an improved gas cylinder plug for the same purpose as the above described plug, but constructed to function in an entirely different manner, whereby the valve in the plug will be moved to a closed position by a part of the grenade launcher to entirely close the intake port of the gas cylinder so that no gases will be admitted thereto.

A particular advantage of the present invention resides in the fact that none of the gases and the carbon carried thereby come into contact with the working parts of the plug, so that the parts are not damaged by the hot gases and their operation is not impeded by an accumulation of carbon.

Various other objects and advantages of the invention will hereinafter become more fully apparent from the following description of the drawing, which illustrates a preferred embodiment thereof, and wherein:

Figure 1 is a longitudinal side elevational view, partly in section, of a portion of gas operated semi-automatic type rifle equipped with a con- I8 of the housing I2.

the improved plug; and

'Figure 2 is a similar view showing the parts with the grenade launcher removed.

Referring more particularly to the drawing, wherein like reference characters designate like or corresponding parts throughout the different views, for the purpose of illustrating one form of the invention, a portion of a semi-automatic gas operated rifle and a rifie grenade launcher have been shown. These parts include the forward portion of the rifle barrel 3, a false muzzle 4 having a bore of slightly greaterdiameter than that of the barrel 3, and which is connected to the forward end thereof by a socket member 5, which forms a part of the gas cylinder 6. A piston rod 1 is slidably mounted'in the gas cylinder 5 and its forward end extends into the reamed out forward end 8 of the gas cylinder, which accommodates the gas cylinder plug. A conventional rifie grenade launcher 9 is shown mounted on the forward end of therifle and latched thereto in the conventional manner by engagement with the bayonet stud l0 thereof. The launcher is only modified in that the rear end of its bore is reamed out to receive the forward end of the false muzzle 4, which is larger externally than the muzzle of the rifle. The parts previously described form no part ofthe present invention but have been disclosed for the purpose of better illustrating the construction and operation of the improved gas cylinder plug, designated generally II, and comprising the invention.

The gas cylinder plug ll includes a housing I2 having a bore l3 opening outwardly at. each end therof and separated intermediate of its ends by a transverse wall or partition l4 having a centrally disposed communicating opening I5 of a smaller diameter than the bores 3. The plug I I is mounted in the reamed out end 8 of the gas cylinder 6 and the inner bore [3 contains a sleeve or bushing I5 having an intake port I! which is disposed for communication with an intake port The muzzle of the barrel 3 is spaced slightly from the adjacent end of the false muzzle 4 to provide a passage I9 which communicates with the intake port l8 to thereby form a gas passage from the bore. of barrel 3 to the portion of the gas cylinder, formed by the sleeve or bushing IS. A valve, designated generally 20, is provided with a piston-like head 2| which is slidably mounted in the bushing I6 and which has a stem 22 extending therefrom through opening I5 and disposed for sliding engagement therewith. The opposite end of the stem 22,

which is disposed in the outer end of the bore I3, is provided with a head 23 forming an abutment for one end of an expansion coil spring 24 the opposite end of which bears against the partition l4 folg.ulfigiilg,.,the.. yalve li forwardly and into an open fposition, asseen in Fig.2. Housing II is provided with an upwardly extending, substantially semi-circular finger 25 which seats in an annular groove 26 in the false muzzle 4 for detachably retaining the plug II in position in the gas cylinder 6. From the foregoing, it will be apparent that when the grenade launcher 9 is applied to the rifle, as shown in Fig. 1 and-as previously, described, its stud 21 will engage the head 23 to depress the valve 20 inwardly and toits position of Fig. 1. With the valve lll thus disposed, its

piston 2| will close and seal intakeport l'l to prevent the propelling gases from the bore of the barrel ;,3, from passingthrough the intake port I 1 into the sleeve l6. Consequently,f'the gasactuatedpistomfl will thus berendered inoperative and will remaininjits forwardmost position, as illpstrated, substantially inengagement with the piston .21 ,so thatvv the, bolt ofthe. -rifle, not shown, willhave ,to-bemanually operated for extracting, ejecting-and;loading either propelling cartridges or ball ammunition. Vii-hen thegrenade launcher s is remoyed, valve will be biased toits open position ofFig. ,2 .by spring 24, .thereby exposing the intalgeport-l 'liand jorming a chamber between pistonztandpiston in the sleeve It to receive ,the eiipanding, propelling gases. When thus; .-,dispo s e d,-[piston,2I will' function as a fixed cylinderhead and the gaspiston Iwillbe driven rea w rd w e ex a d eas -H automatically operating the rifle bolt in the conventional-mar ner, I

Thus -i willbe obviousiith'at thehotpfopelling ,ga es ,;ygill eatall timesexcluded from the valve stem 22,Iopening l spring .24 and the rearportion oi sleeve lfi, so thatthese parts ,will notv be damaged thereby and will not become coated with an ac cumulation oiicarboncarried by. the gases. yariousother, modifications "andicha'nges are i wi e:. eni m a e and. m y be r sq to without de p2;u tingl fron' the spirit and scope of ,the invention as hereinafter defined by the appended-, claims.

, 3 t -openated.. weapon having ,a barrel means, means therein forming a g'as, passag a gascylinder means on said barrel, means having a gas port in register with said gas passage and 4 a piston rod 'slidably associated with the gas cylinder means, the combination therewith of a piston mounted in the gas cylinder means for sliding movement therein to cover the gas port when adjacent the piston rod and to uncover the gas port when spaced, from said piston rod, a grenade launcher on theba'rrel means, and means on the grenade launcher engaging said' piston to move the same adjacent the piston rod to cover the gas port whereby said piston rod is rendered inoperative. 2. In the combination as set forth in claim 1, means associated with said piston yieldingly biasing the, same away from the piston rod to port uncovering position.

3. In a gas-operated firearm having a barrel means, means, therein forming a gas passage, a

gas cylinder means'on the barrel means having a gas port in communication with the gas passage anda piston rod in the gas cylinder means,

the combination therewith of a'pl'ug in the gas cylinder means, a medial partition in said plug and provided with a central orifice, a sleevein one end of said plug abutting said medial partition and slidably receiving the piston rod, said sleeve having a port communicating with the gas port, afpiston slidably, mounted in said sleeve and having a reduced portion slidably received in said central orifice, said piston closing the port in the sleeve when the piston is adj ac ent the piston rod and opening the gas port when said piston is adjacent the said medial partition. 4. In the combination set forth in claim 3, and resilient means yieldingly biasing said piston against the medial partition.

, 5. In the combination set forth in'claim'3, and resilient means biasing said piston against the medial partition,. a grenade launcher mounted on'the barrel means, and a portion on said grenade launcher engaging said piston for holding the piston in port covering position against the bias of the resilient means.

CHARLES H. COATES.

REFERENCES CITED V The ioll'owingreferences are of record in the file of this patent: U

UNITED STATES PATENTS Number Name Date 804,986 Stamm Nov. 21, 1905 853,715 Mondragon May 14, 1907 1,974,851 (Hurst Sept. 25, 1934 2,390,738 Rutherford et a1. Dec. 11, 1945 

